Method for synthesizing methyl butenol through heterogeneous hydrogenation reaction

Abstract

The invention provides a method for synthesizing methyl butenol through heterogeneous hydrogenation reaction. The method comprises the step of catalyzing methyl butynol to prepare methyl butenol through hydrogenation by using a heterogeneous catalyst prepared from a dinitrogen ligand and a cobalt metal precursor. The method provided by the invention solves the problem of low catalyst activity caused by a by-product of a methyl butynol hydrogenation reaction, realizes that the number of times of cyclic application of the catalyst reaches 100 or more, has relatively mild reaction conditions, is simple to operate, is low in cost of the cobalt catalyst, and has high selectivity.

Description

Technical Field

[0001] This invention relates to the field of organic synthesis, and more specifically to a method for preparing methylbutenol by hydrogenation of methylbutynol using a heterogeneous catalyst prepared with a dinitrogen ligand and a cobalt metal precursor. Background Technology

[0002] Methylbutenol is mainly used in the production of isophytol (a major intermediate for vitamin E), chrysanthemic acid (a pyrethroid intermediate), and in the synthesis of vitamin A, vitamin K1, and carotenoid intermediates. It is also used in the synthesis of rubber monomers and fragrances, and is an important building block in organic synthesis. Furthermore, methylbutenol is a key component in the pheromones used to control forest pests (beetles).

[0003] Currently, methylbutenol products are all produced using the acetylene-acetone process, which involves the hydrogenation of methylbutenol. Other processes are still under development. Due to the large-scale production of methylbutenol abroad and the continuous hydrogenation process, it shows certain advantages in terms of production cost and product quality compared to the small-scale production in China. The hydrogenation catalyst for methylbutenol commonly uses the precious metal palladium (patent CN113121315B), but currently, the main problem is poor selectivity (over-hydrogenation byproducts). To improve the selectivity of the reaction, a poisoning agent must be used in conjunction with the precious metal catalyst, making the industrial operation process relatively complex. Furthermore, the loss of palladium metal catalyst during catalyst reuse leads to increased product costs.

[0004] Therefore, in order to realize the development and promotion of low-cost methylbutenol, it is of great significance to develop inexpensive, efficient and recyclable methylbutynol hydrogenation catalysts. Summary of the Invention

[0005] To develop new catalytic systems for the hydrogenation of methylbutynol, this invention provides a method for synthesizing methylbutenol by hydrogenation of methylbutynol using a low-cost heterogeneous cobalt catalyst. The catalyst of this invention has high activity and can be recycled, while also exhibiting very high chemical selectivity, which can significantly reduce the production cost of methylbutenol.

[0006] To achieve the above-mentioned objectives, the present invention provides the following technical solution:

[0007] A method for synthesizing methylbutenol via heterogeneous hydrogenation reaction, comprising using a heterogeneous catalyst prepared from a dinitrogen ligand and a cobalt metal precursor to catalyze the hydrogenation reaction of methylbutynol to prepare methylbutenol.

[0008] In some specific implementations, the dinitrogen ligand has a structure represented by the general formula L:

[0009]

[0010] The R group is a cycloalkyl or substituted cycloalkyl group with 4-12 carbon atoms; the R1 group is methyl or ethyl.

[0011] In some specific embodiments, the cobalt metal precursor is a cobalt salt selected from any one of CoCl2, Co(acac)2 and CoBr2, with CoCl2 being preferred.

[0012] In some specific embodiments, the preparation method of the heterogeneous catalyst includes: under nitrogen protection, adding the cobalt metal precursor to a tetrahydrofuran solution containing the dinitrogen ligand, stirring and mixing, then adding a molecular sieve, stirring and reacting, and after the reaction is completed, removing the solvent under reduced pressure and drying under vacuum to obtain the heterogeneous catalyst.

[0013] In some specific embodiments, the molar ratio of the dinitrogen ligand to the cobalt metal precursor is 1-2, preferably 1.1-1.3;

[0014] In some specific implementations, the mixing temperature is 60-150°C, preferably 90-120°C; the mixing time is 6-24 hours, preferably 18-24 hours.

[0015] In some specific embodiments, the molecular sieve is selected from at least one of MSN-48, MSN-50, MSN-41 and ZSM-5, preferably with 6-10 times the mass of the ligand added to the molecular sieve MSN-48;

[0016] In some specific implementations, the temperature of the stirring reaction is 60-120°C, the stirring reaction time is 2-12 hours, and the preferred reaction conditions are 80-100°C and a stirring reaction time of 6-8 hours.

[0017] In some specific implementations, the vacuum drying temperature is 60-120°C and the time is 12-36 hours, with the preferred condition being drying at 90-100°C for 20-30 hours.

[0018] In some specific embodiments, the amount of the heterogeneous catalyst is 0.001-0.08 wt% of methylbutynol, preferably 0.01-0.05 wt%.

[0019] In some specific embodiments, the hydrogenation reaction is carried out in a solvent, preferably selected from one or more of dichloromethane, 1,2-dichloroethane, dioxane, tetrahydrofuran, diethyl ether, ethylene glycol dimethyl ether, methyl tert-butyl ether, toluene, xylene, n-hexane, and ethanol.

[0020] In some specific implementations, the reaction temperature of the hydrogenation reaction is 40-80°C, preferably 50-60°C; the reaction time is 1-12 hours, preferably 4-6 hours.

[0021] In some specific implementations, the hydrogen pressure of the hydrogenation reaction is 0.8-10 MPa, preferably 4-6 MPa.

[0022] In some specific implementation schemes, the catalyst for the hydrogenation reaction can be reused more than 100 times, with a reaction conversion rate of >99% and a selectivity of >99%.

[0023] Compared with the prior art, the present invention has the following positive effects:

[0024] 1) Compared with traditional catalysts for the hydrogenation of methylbutynol, this heterogeneous cobalt catalyst effectively suppresses the generation of side reactions, exhibits selectivity >99%, mild reaction conditions, and simple operation;

[0025] 2) Under the premise of ensuring reaction selectivity and conversion rate, the catalyst can be recycled more than 100 times;

[0026] 3) The catalyst synthesis raw materials are cheap and the process is simple, and the amount of catalyst used is lower, which can reduce the cost of hydrogenated product methylbutenol by 10%. Attached Figure Description

[0027] Figure 1 Scanning electron microscope (SEM) image of the heterogeneous Co catalyst prepared according to the preparation example of this invention. Detailed Implementation

[0028] To facilitate understanding of the present invention, the following description, in conjunction with embodiments, will further illustrate the invention. It should be understood that the following embodiments are merely for a better understanding of the invention and do not imply that the invention is limited to these embodiments.

[0029] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains. The term "and / or" as used herein includes any and all combinations of one or more of the associated listed items. Locational terms such as top and bottom, mentioned or possibly used in this specification, are defined relative to the constructions shown in the accompanying drawings; they are relative concepts and may therefore vary depending on their location and usage.

[0030] This invention provides a method for synthesizing methylbutenol via heterogeneous hydrogenation reaction, using a heterogeneous catalyst prepared from a dinitrogen ligand and a cobalt metal precursor to catalyze the hydrogenation reaction of methylbutynol to prepare methylbutenol.

[0031] In this invention, the dinitrogen ligand comprises the following types: the ligand has the structure shown in the following formula.

[0032]

[0033] The R group can be a cycloalkyl or substituted cycloalkyl group with 4-12 carbon atoms, such as cyclobutyl, cyclopentyl, cyclohexyl, cycloheptyl, cyclooctyl, methylcyclohexanediamine, etc.; the R1 group is methyl or ethyl.

[0034] Preferably, the dinitrogen ligand is selected from any of the following structures:

[0035]

[0036] The dinitrogen ligand with the above structure can be prepared by the following method: Under nitrogen protection, 1.1 equivalents of 3-chloropropyltrimeth(eth)silane are added dropwise at room temperature to a mixture of cyclohexanediamine (1.0 equivalent), potassium carbonate (1.3 equivalent), and toluene. After the addition is complete, the mixture is heated to 110°C and refluxed for 12 hours. After the reaction is complete, the mixture is allowed to cool naturally to room temperature, filtered to remove salts, washed with water, and the organic solvent is removed under reduced pressure. The concentrate is purified by column chromatography to obtain a ligand with a purity >98%.

[0037] In this invention, the cobalt metal precursor is a cobalt salt, selected from CoCl2, Co(acac)2 and CoBr2, with CoCl2 being preferred.

[0038] In this invention, the synthesis method of the heterogeneous catalyst is as follows: Under nitrogen protection, a solution of tetrahydrofuran containing ligand L is mixed with 1-2 equivalents, preferably 1-1.3 equivalents, of cobalt salt, and stirred at 60-150°C, preferably 90-120°C, for 6-24 hours, preferably 18-24 hours. Then, 6-10 times the mass of the ligand molecular sieve, such as MSN-48, is added, and the mixture is stirred at 60-120°C, preferably 80-100°C, for 2-12 hours, preferably 6-8 hours. After the reaction, the solvent is removed under reduced pressure, and the mixture is vacuum dried at 60-120°C, preferably 90-100°C, for 12-36 hours, preferably 20-30 hours to obtain the Co-based heterogeneous catalyst. The structure of this heterogeneous catalyst is shown below:

[0039]

[0040] The heterogeneous cobalt catalyst of this invention can be used for the hydrogenation of methylbutynol to prepare methylbutenol. The reaction equation is shown below:

[0041]

[0042] In one specific embodiment, the method for preparing methylbutenol by hydrogenation of methylbutynol using the heterogeneous cobalt catalyst of the present invention includes: adding the catalyst into a reaction vessel, stirring at room temperature, adding methylbutynol and solvent under nitrogen protection, and introducing hydrogen gas to carry out the hydrogenation reaction to obtain methylbutenol.

[0043] In this invention, the amount of cobalt catalyst used is 0.001-0.08% of methylbutynol, for example, 0.005%, 0.01%, 0.02%, 0.03%, 0.04%, 0.05%, 0.06%, 0.07%, etc., preferably 0.01-0.05% by mass. This catalyst can be recycled 100 times without significant decrease in activity.

[0044] In this invention, the hydrogenation reaction solvent is preferably one or more selected from dichloromethane, 1,2-dichloroethane, dioxane, tetrahydrofuran, diethyl ether, ethylene glycol dimethyl ether, methyl tert-butyl ether, toluene, xylene, n-hexane, and ethanol.

[0045] In this invention, the temperature of the hydrogenation reaction is preferably 40-80℃, such as 50℃, 60℃, 70℃, 80℃, etc.

[0046] The hydrogen pressure for the hydrogenation reaction described in this invention is preferably 0.8-10 MPa, such as 1 MPa, 2 MPa, 3 MPa, 4 MPa, 5 MPa, 6 MPa, 7 MPa, 8 MPa, 9 MPa, etc., and preferably 3-6 MPa.

[0047] In this invention, the reaction time of the hydrogenation reaction is 1-12 hours, for example 2 hours, 3 hours, 4 hours, 5 hours, 6 hours, 7 hours, 8 hours, 9 hours, 10 hours, 11 hours, etc., preferably 4-6 hours.

[0048] The present invention will be further explained and illustrated below through more specific embodiments, but these do not constitute any limitation.

[0049] Main raw material sources

[0050] Methylbutynol: 99%, Inokai;

[0051] Pa / C: Connor;

[0052] Cobalt metal precursor and 3-chloropropyltrimeth(eth)silane: Inokai;

[0053] o-diamine compounds: SigmaAldrich or AHHChemical.

[0054] Main testing methods

[0055] The catalyst activity of the hydrogenation reaction was determined by qualitative and quantitative analysis of the components in the reaction solution. The conditions of the GC analytical instrument used were as follows:

[0056] Instrument Model: Shimadzu GC2010

[0057] Column: DB-5 (30m 0.25mm 0.25μm)

[0058] Column temperature program: First, maintain at 35℃ for 10 min, then increase to 250℃ at a rate of 10℃ / min, and maintain at this temperature for 10 min.

[0059] Detector temperature: 300℃

[0060] Carrier gas: 1 bar

[0061] Air: 0.3 bar

[0062] Gas (H2): 0.3 bar

[0063] Sample quality analysis was performed using the internal standard method. It should include:

[0064]

[0065] In the formula, m1 is the mass of a certain product, m is the mass of the internal standard, a1 is the peak area of ​​the product detected in gas chromatography, and a is the peak area of ​​the internal standard. k is a correction coefficient related to the analyte and detection conditions.

[0066] Preparation Example 1

[0067] Under nitrogen protection, 28.03 g (110 mmol) of 3-chloropropyltriethoxysilane was added dropwise at room temperature to a mixture of 11.42 g (100 mmol), potassium carbonate (18.0 g, 130 mmol), and 25 mL of toluene. After the addition was complete, the mixture was heated to 110 °C and refluxed for 12 hours. After the reaction was complete, the mixture was allowed to cool naturally to room temperature, filtered to remove salts, and then washed three times with 100 mL of water. The organic phases were combined and the organic solvent was removed under reduced pressure. The concentrate was purified by column chromatography (PE / EtOAc=5 / 1) to obtain ligand L1 with a purity >98% (¹H NMR (400MHz, CDCl3): δ 5.11 (s, 2H), 3.83 (q, J=14Hz, 6H), 2.85–2.78 (m, 2H), 2.60–2.55 (m, 2H), 2.0 (s, 1H), 1.74–1.64 (m, 4H), 1.60–1.4). 6(m,2H),1.25-1.21(m,4H),1.21(t,J=12Hz,9H),0.58(t,J=12Hz,2H);13CNMR(101MHz,CD Cl3): δ8.1,18.1,23.9,25.7,32.0,32.6,35.9,52.0,56.0,58.9,64.5; 29SiNMR: δ−43.8.).

[0068]

[0069] Under nitrogen protection, ligand L1 (16.0 g, 50 mmol) was dissolved in 50 mL of anhydrous tetrahydrofuran, and CoCl2 (6.5 g, 50 mmol) was added. The mixture was stirred at 100 °C for 18 hours, followed by the addition of 128 g of molecular sieve MSN-48 (8 times the mass of the ligand), and the mixture was stirred at 100 °C for 6 hours. After the reaction was complete, the solvent was removed under reduced pressure, and the mixture was dried under vacuum at 100 °C for 24 hours to obtain the Co-based heterogeneous catalyst Cat1. The structure of this heterogeneous catalyst and its scanning electron microscopy structure are shown below. Figure 1 As shown in the diagram below, the structure illustrates the dinitrogen ligand and cobalt metal active component loaded on the molecular sieve support.

[0070]

[0071] Preparation Example 2

[0072] In Preparation Example 1, the cyclohexanediamine was replaced with an equimolar amount of cyclopentanediamine, and other conditions were the same as in Preparation Example 1. The resulting ligand and catalyst structures are as follows:

[0073]

[0074] Preparation Example 3

[0075] In Preparation Example 1, cyclohexanediamine was replaced with an equimolar amount of cyclobutanediamine, and other conditions remained the same as in Preparation Example 1. The resulting ligand and catalyst structures are as follows:

[0076]

[0077] Preparation Example 4

[0078] In Preparation Example 1, the cyclohexanediamine was replaced with an equimolar amount of cycloheptanediamine, and other conditions were the same as in Preparation Example 1. The resulting ligand and catalyst structures are as follows:

[0079]

[0080] Preparation Example 5

[0081] In Preparation Example 1, cyclohexanediamine was replaced with an equimolar amount of cyclooctanediamine, and other conditions remained the same as in Preparation Example 1. The resulting ligand and catalyst structures are as follows:

[0082]

[0083] Preparation Example 6

[0084] The cyclohexanediamine in Preparation Example 1 was replaced with an equimolar amount of bicyclo[2.2.1]heptane-2,3-diamine, and other conditions were the same as in Preparation Example 1. The structures of the resulting ligand and catalyst are as follows:

[0085]

[0086] Example

[0087] Heterogeneous cobalt catalyst Cat1, methylbutyninol (42 g, 0.5 mol), and 60 ml of solvent were added to a 250 ml reactor. After purging with nitrogen three times, hydrogen was introduced for pressurization, and heating was initiated. Catalytic hydrogenation was carried out under different temperatures, pressures, and reaction times, and samples were taken for GC analysis. Specific reaction conditions are detailed in the table below:

[0088] Example Cat1 solvent Temperature ℃ Pressure MPa Time h Conversion rate / selectivity% 1 0.05wt% Toluene 50 5 6 99 / 98 2 0.05wt% Toluene 50 4 6 99 / 98 3 0.05wt% Toluene 50 3 6 99 / 98 4 0.05wt% Toluene 50 2 6 99 / 98 5 0.05wt% Toluene 50 2 8 99 / 98 6 0.05wt% Toluene 60 4 6 99 / 98 7 0.05wt% Toluene 80 4 4 99 / 98 8 0.05wt% Toluene 40 4 6 99 / 98 9 0.05wt% Toluene 30 4 6 99 / 98 10 0.05wt% ethanol 50 4 6 99 / 99 11 0.05wt% acetone 50 4 6 99 / 99 12 0.05wt% Tetrahydrofuran 50 4 6 99 / 99 13 0.05wt% dichloromethane 50 4 6 99 / 98 14 0.05wt% n-Hexane 50 4 6 99 / 98 15 0.03wt% Toluene 50 4 6 99 / 98 16 0.03wt% Toluene 50 4 8 99 / 98 17 0.01wt% Toluene 50 4 6 99 / 98 18 0.01wt% Toluene 50 4 10 99 / 98

[0089] The hydrogenation operation of the series of heterogeneous cobalt catalysts prepared in the preparation example is the same as that in Example 10. The specific reaction conditions and results are shown in the table below:

[0090] Example catalyst solvent Temperature ℃ Pressure MPa Single batch time h Conversion rate / selectivity% 19 Cat1 ethanol 50 4 6 99 / 99 20 Cat2 ethanol 50 4 6 99 / 98 21 Cat3 ethanol 50 4 6 99 / 97 22 Cat4 ethanol 50 4 6 99 / 98 23 Cat5 ethanol 50 4 6 99 / 98 24 Cat6 ethanol 50 4 6 98 / 99

[0091] Further considering the issue of catalyst recycling, the specific recycling operation is as follows:

[0092] In Example 10, homogeneous cobalt catalyst Cat1, methylbutyninol (42 g, 0.5 mol), and 60 ml of solvent were added to a 250 ml reactor. After purging with nitrogen three times, the reactor was pressurized with hydrogen. Catalytic hydrogenation was carried out at the reaction temperature, pressure, and time specified in the table below, and samples were taken for GC analysis. After this batch of reaction was completed, the pressure was released and nitrogen was introduced under slight positive pressure. The reaction pressure was used to expel the reactants, and the catalyst was filtered through a filter head and remained in the reactor. Under nitrogen protection, the next batch of raw material solution was pumped into the reactor using a horizontal flow pump. After purging with hydrogen three times and pressurizing to the corresponding pressure, heating and stirring were started, and the reaction was sampled for analysis.

[0093] Example Cat1 solvent Temperature ℃ Pressure MPa Single batch time h Number of times to apply Last conversion rate / selectivity% 25 0.05wt% ethanol 50 5 6 25 99 / 99 26 0.05wt% ethanol 50 5 6 40 99 / 99 27 0.05wt% ethanol 50 5 6 100 99 / 99 28 0.02wt% ethanol 50 5 6 25 99 / 99 29 0.02wt% ethanol 50 5 6 40 99 / 99 30 0.02wt% ethanol 50 5 6 80 98 / 99

[0094] Comparative Example 1

[0095] In a glove box, the mixed catalyst Pd / C (0.05 wt%) was weighed, and methylbutynol (42 g, 0.5 mol) was added to the reactor, followed by toluene (60 ml). The reactor was then sealed and removed from the glove box to prepare for the reaction. After purging with hydrogen five times, the hydrogen pressure was increased to 5 MPa, and the heating was turned on at 50°C for 6 hours. GC sampling and analysis showed that the raw material methylbutynol had basically reacted completely, and the product methylbutenol had a conversion rate of 99% and a selectivity of 90%.

[0096] Comparative Example 2

[0097] In a glove box, the catalyst RaneyNi (0.05 wt%) was weighed, and methylbutynol (42 g, 0.5 mol) was added to the reactor, followed by toluene (60 ml). The reactor was then sealed and removed from the glove box to prepare for the reaction. After purging with hydrogen five times, the hydrogen pressure was increased to 5 MPa, and the heating was turned on at 50°C for 6 hours. GC sampling and analysis showed that the raw material methylbutynol had basically reacted completely, and the product methylbutenol had a conversion rate of 99% and a selectivity of 86%.

[0098] It is readily understood that the above embodiments are merely illustrative examples for clear explanation and do not imply that the invention is limited thereto. Those skilled in the art will recognize that other variations or modifications can be made based on the above description. It is neither necessary nor possible to exhaustively list all possible implementations here. However, obvious variations or modifications derived therefrom remain within the scope of protection of this invention.

Claims

1. A method for synthesizing methylbutenol via heterogeneous hydrogenation reaction, characterized in that, The hydrogenation reaction of methylbutynol to prepare methylbutenol was catalyzed by a heterogeneous catalyst prepared with dinitrogen ligand and cobalt metal precursor.

2. The method according to claim 1, characterized in that, The aforementioned dinitrogen ligand has a structure represented by the general formula L: The R group is a cycloalkyl or substituted cycloalkyl group with 4-12 carbon atoms; the R1 group is methyl or ethyl.

3. The method according to claim 1, characterized in that, The cobalt metal precursor is a cobalt salt selected from CoCl2, Co(acac)2 and CoBr2, with CoCl2 being preferred.

4. The method according to any one of claims 1-3, characterized in that, The preparation method of the heterogeneous catalyst includes: under nitrogen protection, adding the cobalt metal precursor to a tetrahydrofuran solution containing the dinitrogen ligand, stirring and mixing, then adding a molecular sieve, stirring and reacting, removing the solvent under reduced pressure after the reaction is completed, and drying under vacuum to obtain the heterogeneous catalyst.

5. The method according to claim 4, characterized in that, The molar ratio of the dinitrogen ligand to the cobalt metal precursor is 1-2, preferably 1.1-1.3; and / or The mixing temperature is 60-150℃, preferably 90-120℃; the mixing time is 6-24 hours, preferably 18-24 hours. Preferably, the molecular sieve is selected from at least one of MSN-48, MSN-50, MSN-41, and ZSM-5, and more preferably, 6-10 times the ligand mass of molecular sieve MSN-48 is added; and / or The stirring reaction is carried out at a temperature of 60-120℃ for 2-12 hours, preferably at a temperature of 80-100℃ for 6-8 hours; and / or The vacuum drying temperature is 60-120℃ and the time is 12-36 hours, with the preferred condition being drying at 90-100℃ for 20-30 hours.

6. The method according to claim 1, characterized in that, The amount of the heterogeneous catalyst is 0.001-0.08 wt% of methylbutynol, preferably 0.01-0.05 wt%.

7. The method according to claim 1 or 6, characterized in that, The hydrogenation reaction is carried out in a solvent, preferably selected from one or more of dichloromethane, 1,2-dichloroethane, dioxane, tetrahydrofuran, diethyl ether, ethylene glycol dimethyl ether, methyl tert-butyl ether, toluene, xylene, n-hexane, and ethanol.

8. The method according to claim 7, characterized in that, The hydrogenation reaction is carried out at a temperature of 40-80°C, preferably 50-60°C, and for a reaction time of 1-12 hours, preferably 4-6 hours.

9. The method according to claim 8, characterized in that, The hydrogen pressure in the hydrogenation reaction is 0.8-10 MPa, preferably 4-6 MPa.

10. The method according to any one of claims 1-9, characterized in that, The catalyst for the hydrogenation reaction can be reused more than 100 times, with a reaction conversion rate of >99% and a selectivity of >99%.

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